Vehicle seats in recreational watercraft have included flip up bolster systems for a number of years. Typically, flip up bolster systems involve having the forward edge of the seating surface (bolster) as a separate part from the rear portion of the seating surface. This forward portion of the seat complete with padding, upholstery and a structural core is connected to the remainder of the seat with a hinging system or mechanical linkage that enables the forward portion of the seat to rotate or slide back and up with respect to the remainder of the seating surface until the forward portion of the seat is suspended several inches above the rear portion of the seat. In the raised position, the bolster provides a higher seating position for the operator and or passenger of the vehicle.
Operating or riding in a watercraft with the bolster in the raised position allows better visibility than would be possible if the bolster was not elevated. When a watercraft is accelerating from slow speed operation to higher speed operation, the bow of the boat often rises significantly, temporarily restricting the occupant's visibility of the area immediately in front of the boat. By moving the bolster of the seat to the raised position, and occupying that position, the operator can significantly improve his or her field of vision. A raised seating position in a watercraft can also be advantageous when the occupants wish to look carefully down into the water to see submerged obstacles or to look for objects on the water such as water skiers, lines, docks, floating debris, fishing lures, etc.
Improving the visibility of the operator and or passenger of a boat can significantly reduce the likelihood of collisions with unseen objects, so seats with flip up bolsters are viewed as a safety enhancement. Seats with flip up bolsters are now becoming the norm in marine seating.
For marine seats with flip up bolsters, the seat is typically composed of a bucket seat shell that provides a means of supporting the other components of the seat. Generally the bucket seat shell is composed of a back area, two arm areas and a lower area connecting the arms and back that provides a surface where this shell can be connected to mounting hardware below the seat. The back and arms of the shell are typically fully upholstered with urethane foam padding and a vinyl skin is stapled in place to cover the exposed areas of the shell. Generally, there is a separate seat pan that creates the rear of the seating surface. The seat pan is composed of a structural substrate component and on top of that component, there is a urethane foam cushion. Covering the foam cushion is a vinyl skin that is stapled in place. The upholstered seat pan is generally mounted on the lower connecting surface of the seat shell using screws. The seat pan may also incorporate a shock absorption system in some designs.
The forward portion of the seating surface or bolster typically extends four to six inches back from the front edge of the seating surface. Generally the bolster is composed of a structural but hollow core that is padded with urethane foam on the upper and front edges and then wrapped in vinyl film that is stapled in place to complete the upholstery. There are several means currently being employed for allowing the bolster to move between the lower and upper positions. The first system keeps the bolster in the same vertical orientation when it reaches the raised position. This is accomplished by using a pair of two bar linkage mechanisms with that are attached at each end of the hollow bolster using screws. The two linkage mechanisms are also attached to the seat shell at or near the intersection of the arms of the shell with the lower connecting area of the shell using screws. A fully upholstered seat pan is positioned immediately to the rear of the bolster and between the linkage arms using screws or bolts. A gap between the seat pan and the arms of the shell is provided for the linkage arms to move and the linkages are visible in this gap when the bolster is in the lower position and viewed from above.
The two bar mechanisms are very costly to fabricate and to install in the seat. Typically these mechanisms are composed of a fairly large number of components and are fabricated from aluminum that must be painted in order to resist corrosion and to have an acceptable visual appearance. In addition to the cost to fabricate the linkage mechanisms, assembly to the seat is also costly due to the large number of fasteners required. Because the painted linkage arms are visible at each side of the bolster, overall appearance of the chair suffers because the arms cannot be color-matched to the vinyl in an effective manner.
A second design for these types of mechanisms is to have a metal hinge mechanism in place of the two bar links mentioned in the previous construction. These hinged systems rotate the bolster ninety degrees as it is moved to the raised position, allowing the forward vertical edge of the bolster to become the seating surface. The mechanism is composed of a metal bracket that is fixed to the seat shell using screws. Extending outwards from each bracket is a pivot arm that is free to rotate approximately ninety degrees. This arm is typically connected to a hollow or solid structural bolster that is padded with a urethane foam cushion material and upholstered. Shortcomings of this construction include the cost and painting of the aluminum components and high assembly costs.
Another significant shortcoming of this design is that the hinge system does not provide a forward lock when the bolster is in the raised position. Absence of such a lock allows the bolster to fold down suddenly when the operator shifts his weight as might occur during rough wave conditions. The resulting change in position for the operator could lead to loss of control of the watercraft.
A third construction technique for marine seats with flip up bolsters utilizes a hollow molded bolster mechanism that has hollow arms extending rearwards from the bolster. These arms are several inches across, and the complete bolster part is shaped like a U when viewed from above. The arms contain protrusions that extend into holes within the arm areas of the outer shell of the seat. The protrusions on the bolster arms and recesses in the shell contain corresponding stops that prohibit rearward movement of the bolster when it is in the raised position. The recesses also control rotation of the bolster. The bolster also rests against stops when it is in the lowered position. Typically, the top and front surfaces of the bolster are padded with urethane foam, and the entire assembly must be wrapped in vinyl film that has a zipper sewn to the vinyl.
There are several disadvantages with the previously mentioned construction. Because of the thickness of the arms for the bolster, they intrude several inches into the seating area from the inside of either arm of the seat shell. This protrusion limits the size of the seat pan and detracts from the overall comfort of the seat. In addition, if an internal suspension is included in the seat pan, the limited space reduces the size and shock absorption capabilities of the suspension system.
The hollow bolster in this system is typically manufactured using the blow-molding process. Because the blow-molding process is not capable of producing parts with tight tolerance control, the force required to rotate the bolster from the lower to the raised position varies considerably as a result of wide variations in dimensions required by the process. This is not a desirable condition since consistently smooth and easy movement of the bolster is desirable.
Another disadvantage of this construction is that the bolster component is difficult and costly to upholster due to its U shaped nature. And, the U shape limits the styling possibilities for the seat as well. The presence of the thick arms also precludes the inclusion of raised areas at the edges of the seat cushion that are often included in seat cushions. These raised areas are intended to give the occupant a feeling of security while occupying the seat.
Another significant shortcoming of this design is that this system does not provide a forward lock when the bolster is in the raised position. Absence of such a lock can allow the bolster to fold down suddenly when the operator shifts his weight as might occur during rough wave conditions. The resulting change in position for the operator could lead to loss of control of the watercraft.
Finally, the assembly technique for this design requires that the assembler flex the bolster arms inward to allow insertion of the locking protrusions on the arms into the holes of the arms of the seat shell. This requires considerable force and not all workers are capable of completing the task.